I've noticed that a lot of the custom roms out there have a black market. Im not sure, but if i extract the apk from one of those roms and put it on my phone (stock rooted at the moment) would it still work? thanks for any responses.
Yes. Backup your current Market.apk and replace it with the black one from the custom ROM and it should work fine.
The Market.apk lives in /system/app/. You have to use either Root Explorer or ADB to replace it. I would recommend ADB, but either will work.